Repeater for power line communication system

ABSTRACT

The invention relates to a method and a device ( 1 ) for data transmission in a power supply network (power line communication). The device ( 1 ), preferably centrally located in a distribution box ( 6 ), is equipped with transceivers ( 3, 4, 5 ), each one of which is connected to a phasing line ( 11, 12, 13 ) of the power supply network, from which it can receive data, and to which it can transmit data. The transceivers are coupled via a control unit ( 2 ), wherein the control unit ensures that the data received from a phasing line can be transmitted, prepared, on at least one other phasing line. Hereby, a re-transmission on all phasing lines with the same transmission power, or a re-transmission matched to the particular signal strengths or the addressees of the data, can take place.

The invention relates to a method and a device for data transmission ina power supply network.

The designation “Power Line Communication” (PLC) relates to a knownmethod by which data is transmitted via the electrical lines of a powersupply network which is intended per se for the supply of electricity.The advantage of a power line communication of this kind lies in thefact that, in more or less every household, lines belonging to the powersupply network are present in virtually every room, making it possibleto cross-link appliances in different rooms without the need forrewiring. Whilst, in this respect, by virtue of outdated statutoryprovisions, only small frequency ranges have hitherto been permitted onpower supply lines for the transmission of signals, these restrictionswill be lifted in the future, making data rates of more than 10 Mbit/spossible. Power line communication can be used here both as a maininfeed in the sense of a “last mile” for infeeding the Internet via thepower supply network, and also in setting up an in-home network. Usingthe high data rates referred to, it would, for example, be possible tosend the signal from a video recorder from the living room directly to atelevision in a different room without additional cables.

However, the use of power supply lines for data communication encountersa number of technical difficulties, such as:

-   -   high attenuation as a result of detours of the line installation        (also where sockets are located close together in some cases).    -   inadequate transmission between different phasing lines of the        power supply network. According to the prior art, passive phase        couplers are used in the distribution box for transmission        between different phasing lines, as a result of which, however,        the transmission power is distributed among the various phasing        lines and is thereby reduced.    -   the existence of numerous interference sources, including, in        principle, every electronic appliance.    -   the low permitted transmission power.

In order to solve some of the problems outlined above, it is known fromWO 00/21212 for repeaters to be arranged, spaced apart from one another,along a phasing line of a power supply network, which repeaters canreceive the data signal transmitted on the phasing line by means of areceiver, decode it and subsequently transmit it, amplified, back to thephasing line by means of a transmitter.

Against this background, it was an object of the present invention toprovide a method and a device which enable an improvement of power linecommunication in power supply networks with multiple phasing lines.

This object is achieved by means of a method with the features asclaimed in claim 1 and by a device with the features as claimed in claim6. Advantageous embodiments are described in the dependent claims.

In a method for data transmission in a power supply network inaccordance with the invention (so-called power line communication), thedata transmitted on a phasing line of the power supply network isreceived and then re-transmitted. The method is characterized by thefact that the data is re-transmitted on at least one phasing linedifferent from the phasing line from which it was received. There-transmission of the data preferably takes place at the maximumpermitted power.

A method of this kind safeguards the transmission of data betweendifferent phasing lines of a power supply network by actively passing ondata transmitted on a phasing line to at least one different phasingline. Since, in particular, an amplification of the signals can alsotake place hereby, a reduction of the maximum attenuation to one halfand a tripling of the effective transmission power per phasing line canbe achieved with this method. In this manner, the reliability of thepower line communication is ensured.

Using this method, the data received from a first phasing line can bere-transmitted on at least one different phasing line and, additionally,on the first phasing line. In this manner, a repeater function isrealized on the first phasing line, which repeater function leads to theamplification of a weak signal. In particular, the data received from afirst phasing line can subsequently be re-transmitted on all phasinglines of the power supply network using this method, preferably at themaximum permitted transmission power (“standard repeater”). A repetitionof this kind of the data, with the same strength on all phasing lines,requires a minimal amount of control.

In accordance with a development of the method, the data may also bere-transmitted only on the phasing lines of the power supply network onwhich its original signal strength was weak, i.e. lay below a thresholdvalue. In this manner, an “adaptive repeater” can be obtained, whichrepeats the signal only on the phasing lines on which no reception wasyet likely.

In accordance with another development of the method, the data may alsobe re-transmitted on only the phasing lines of the power supply networkto which the addressees of the particular data are connected. In thecase of an “intelligent repeater” of this kind, which phasing lines areconnected to which appliances must be known, for instance by means ofanalysis of associated response signals. If one of these appliances isthen subsequently addressed by data on a phasing line of the powersupply network, this data can specifically be passed on to that phasingline at which the addressee (appliance) is located.

Further, it is advantageous if, with this method, line management isalso undertaken, in which data is prepared before being re-transmitted.The preparation may, in particular, comprise channel equalization andchannel matching. To this end, recourse is preferably had to apreviously undertaken channel analysis.

The invention further relates to a device for data transmission in apower supply network (power line communication), which device comprisesa receiver for receiving data transmitted on a first phasing line of thepower supply network, and a transmitter for transmitting data on asecond phasing line of the power supply network. The device ischaracterized in that the first and second phasing lines are different.This means that the data transmitted on the first phasing line andreceived by the receiver can be passed on, with the device, via thetransmitter to a different (second) phasing line, so that the device, inthe context of the method explained above, brings about a coupling ofthe different phasing lines.

The device hereby preferably comprises a receiver and a transmitter foreach phasing line of the power supply network, wherein all receivers andtransmitters are coupled together by a control unit of the device. Inthis manner it is possible to receive data from any one of the phasinglines and to pass it on to at least any one other phasing line.

The device and/or its control unit may also be set up in such a way thatthe device can execute a method of the type explained above. This meansthat it can execute, in particular, the functions of the explainedstandard repeater, of an adaptive repeater, intelligent repeater and/orline management.

Furthermore, the device may preferably comprise a (bulk) storage devicefor the temporary storage of data transmitted on the phasing lines ofthe power supply network. With the aid of this storage device, it isthen possible, with appropriate programming of the control unit of thedevice, for the device to operate centrally to undertake standbyfunctions for all appliances connected to the power supply network, sothat these can be completely switched off.

Furthermore, the device may be equipped with additional transmitting andreceiving modules, which enable connection and communication with othertransmission methods and networks. In this manner, the device canoperate as a universal or adaptable coupling module between differenttransmission networks.

Furthermore, the device may be equipped with an additional networkfilter in order to improve the separation of an “in-home network” froman “access network”, which, for example, ensures access to the Internet,and thereby to increase the possible data rate in the home. Hereby, afurther transmitter and receiver may preferably be integrated on theaccess side, and selected data may be routed past the filter.

The invention will be further described with reference to an example ofan embodiment shown in the drawing, to which, however, the invention isnot restricted.

The FIGURE shows schematically the structure of a power linecommunication with a device in accordance with the invention forcoupling different phasing lines.

The upper part of the FIGURE shows an in-home network based on a powerline communication, in which various appliances 20-25 are connected tothe three phasing lines 11, 12 and 13 of a power supply line 10. Theseappliances may be, for example, a television 20, a video recorder 21 anda hard disk (HD) video recorder 22 on a first phasing line 11, a PC 23on a second phasing line 12, and a washing machine 24 and a furtherappliance 25 on a third phasing line 13. In a configuration of thiskind, problems of communication between two appliances (such as thevideo recorder 21 and the PC 23), which are connected to differentphasing lines 11, 12, may occur.

In order to solve this problem, a repeater 1 is connected in accordancewith the invention to the phasing lines 11, 12 and 13, wherein therepeater 1 is preferably installed in a central location in the meterbox 6 or in a subsidiary distribution box. The only importantconsideration, however, is that the repeater 1 can be installed in alocation at which access exists to all phases of the power supplynetwork that are used in the building or dwelling, such as the cookerconnection that is present in virtually every dwelling.

For each of the phasing lines 11, 12, 13, repeater 1 comprises a powerline transceiver 3, 4, 5, each of which has a receiver for receivingdata from a phasing line, and a transmitter for transmitting data on(the same) phasing line. As shown, transceiver 3 is connected to phasingline 11, transceiver 4 is connected to phasing line 12, and transceiver5 is connected to phasing line 13.

Furthermore, all three transceivers 3, 4, 5 are coupled to a controlunit 2. The control unit 2 may be of various designs in order to realizefunctions of different complexities. In the simplest case, as a standardrepeater, it can uniformly pass the signal, received from one line, e.g.phasing line 11, and prepared, to all phasing lines 11, 12, 13.Conversely, in the case of operation as an adaptive repeater, theprepared signal is passed only to the phasing lines on which theoriginal signal was weak, i.e. where no reception was yet likely. In thecase of operation as an intelligent repeater, control unit 2additionally analyses, on the basis of the associated response signals,to which phasing lines which appliances are connected. There-transmitted information is then only ever transmitted on the lines atwhich the particular addressee is located. Finally, in the case of linemanagement, repeater 1 can also simultaneously assume the function ofchannel analysis and, where this is possible and necessary, ofcompensation and matching.

The central arrangement of repeater 1 simultaneously solves the problemsof attenuation, of phase coupling and of signal-to-noise ratio. Byretrofitting existing installations with repeater 1, ultimatereliability and high data rates can be ensured, even in problematiccases.

LIST OF REFERENCE NUMBERS

-   1 Repeater in accordance with the invention-   2 Control unit-   3, 4, 5 Power line transceivers-   6 Meter box-   10 Power supply line-   11, 12, 13 Phasing lines-   20 Television-   21 Video recorder-   22 HD video recorder-   23 PC-   24 Washing machine-   25 Appliance

1. A method for data transmission in a power supply network, whereindata transmitted on a particular phasing line (11) of the power supplynetwork is received and then re-transmitted, characterized in that thedata is re-transmitted on at least one phasing line (12, 13) differentfrom the said phasing line (11).
 2. A method as claimed in claim 1,characterized in that the data is re-transmitted on all phasing lines(11-13).
 3. A method as claimed in claim 1, characterized in that thedata is re-transmitted on the phasing lines (11-13) on which itsoriginal signal strength lay below a threshold value.
 4. A method asclaimed in claim 1, characterized in that the data is re-transmittedonly on the phasing lines (11-13) to which the addressees (20-25) of thedata are connected.
 5. A method as claimed in claim 1, characterized inthat a preparation, in particular a channel equalization and channelmatching, is undertaken before the re-transmission.
 6. A device (1) fordata transmission in a power supply network, comprising a receiver (3-5)for receiving data transmitted on a first phasing line (11-13) of thepower supply network, and a transmitter (3-5) for transmitting data on asecond phasing line (12-13) of the power supply network, characterizedin that the first and second phasing lines are different.
 7. A device asclaimed in claim 6, characterized in that it comprises a receiver and atransmitter (3-5) for each phasing line (11-13) of the power supplynetwork, and that all receivers and transmitters are coupled together bya control unit (2).
 8. A device as claimed in claim 6, characterized inthat it comprises a storage device for the temporary storage of datatransmitted on the phasing lines (11-13) of the power supply network. 9.A device as claimed in claim 6, characterized in that it is equippedwith additional transmitting and receiving modules for connection toother networks with different transmission methods.
 10. A device asclaimed in claim 6, characterized in that it is equipped with anadditional network filter for separation of an in-home network from anexternal network, wherein a further transmitter and receiver arepreferably integrated on the external side, and selected data is routedpast the filter.